Application of IR thermography for evaluating the integrity of a natural gas delivery station

Abstract

The paper explores possibilities of applying the IR thermography for integrity evaluation and quick detection of failures in natural gas delivery stations. The natural gas stations typically comprise overground facilities for filtering, pressure reduction, flow metering and odorizing. The facilities and the interconnecting pipelines are subject to risk of damages due to material failures or external factors. The failure detection algorithm presented in the paper is based on two physical phenomena concerning the temperature of piping. The first one is bound to the process of natural gas expansion to the atmosphere leading to a rapid decrease of the gas temperature, usually below the ambient temperature. Therefore, the flux of gas absorbs heat from the pipe walls implying a local drop of the surface temperature. The second phenomenon is related to the change of the flow pattern in the station, since leakages typically induce high discharge flow rates. The new flow pattern affects the thermal effect exerted by the gas flux on the pipe walls, hence significant variations from previous values as well as from the ambient conditions may be registered in short-time intervals. The algorithm implements integrity test procedures based on both thermal mechanisms, as well as initializing procedures for image normalization and identification of relevant pipeline sections.